Class: RubyPgExtras::MissingFkConstraints

Inherits:
Object
  • Object
show all
Defined in:
lib/ruby_pg_extras/missing_fk_constraints.rb

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.call(table_name, ignore_list: nil) ⇒ Object

ignore_list: array (or comma-separated string) of entries like:

  • “posts.category_id” (ignore a specific table+column)

  • “category_id” (ignore this column name for all tables)

  • “posts.*” (ignore all columns on a table)

  • “*” (ignore everything)



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# File 'lib/ruby_pg_extras/missing_fk_constraints.rb', line 10

def self.call(table_name, ignore_list: nil)
  new.call(table_name, ignore_list: ignore_list)
end

Instance Method Details

#call(table_name, ignore_list: nil) ⇒ Object 



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# File 'lib/ruby_pg_extras/missing_fk_constraints.rb', line 14

def call(table_name, ignore_list: nil)
  ignore_list_matcher = IgnoreList.new(ignore_list)

  tables =
    if table_name
      [table_name]
    else
      all_tables
    end

  schemas_by_table = query_module
    .table_schemas(in_format: :hash)
    .group_by { |row| row.fetch("table_name") }

  fk_columns_by_table = query_module
    .foreign_keys(in_format: :hash)
    .group_by { |row| row.fetch("table_name") }
    .transform_values { |rows| rows.map { |row| row.fetch("column_name") } }

  tables.each_with_object([]) do |table, agg|
    schema = schemas_by_table.fetch(table, [])
    fk_columns_for_table = fk_columns_by_table.fetch(table, [])
    schema_column_names = schema.map { |row| row.fetch("column_name") }

    candidate_fk_columns = schema.filter_map do |row|
      column_name = row.fetch("column_name")

      # Skip columns explicitly excluded via ignore list.
      next if ignore_list_matcher.ignored?(table: table, column_name: column_name)

      # Skip columns that already have a foreign key constraint on this table.
      next if fk_columns_for_table.include?(column_name)

      # Skip columns that don't look like an FK candidate based on naming conventions.
      next unless DetectFkColumn.call(column_name, all_tables)

      # Rails polymorphic associations use <name>_id + <name>_type and can't have FK constraints.
      candidate_prefix = column_name.delete_suffix("_id")
      polymorphic_type_column = "#{candidate_prefix}_type"
      # Skip polymorphic associations (cannot be expressed as a real FK constraint).
      next if schema_column_names.include?(polymorphic_type_column)

      column_name
    end

    candidate_fk_columns.each do |column_name|
      agg.push(
        {
          table: table,
          column_name: column_name,
        }
      )
    end
  end
end